色氨酸残基在内切葡聚糖酶分子中的作用

内切葡聚糖酶的化学修饰研究表明：色氨酸残基可能位于活性位点，与底物结合有关．荧光光谱测定指出该酶的荧光几乎都来自色氨酸残基，酶分子中色氨酸微环境对ｐＨ变化非常敏感，降低ｐＨ导致了酶分子构象发生了较大变化，配基结合使酶分子色氨酸微环境产生了改变，引发了与ｐＨ诱导不同的构象变化．

Role of Tryptophan Residue in Endoglucanase from Trichoderma pseudokoningii S 38

The modification of N bromosuccinimide(NBS)resulted in a complete loss of the activity of the endoglucanase from Trichoderma pseudokoningii S 38,but did not cause a large conformational change of the enzyme,suggesting that tryptophan residues may be involved in the enzyme active site.The inactivation caused by NBS resulted in an increasing K m value,but did not influence the catalytic function.This indicated that the tryptophan may be relevent to the substrate binding function.The results from observations of the fluorescence changes caused by pH inducing and ligands binding suggested that the microenvironments of tryptophan residues in the enzyme were sensitive to the change of pH.Decreasing pH resulted more exposed tryptophan residues to the solvent.However,the environments of tryptophan residues were not changed by pH inducing after binding to ligands.